textproduct: Albany

WHAT HAS CHANGED

Confidence continues to increase in a light to moderate snowfall late Monday night through Tuesday, as a clipper system moves across the region.

KEY MESSAGES

1. A cold front will bring some snow showers to mainly higher terrain areas late tonight into Sunday morning. This will be followed by a period of lake effect snow Sunday afternoon in the western Mohawk Valley and southwest Adirondacks, with gusty northwest winds developing across the area.

2. Confidence continues to increase in the potential for a light to moderate snowfall late Monday night through Tuesday, which could impact both the morning and evening commutes as well as any pre- holiday travel.

3. Temperatures continue to trend above normal for later next week, with some chances for mainly rain with some high elevation wintry precipitation possible at times.

DISCUSSION

KEY MESSAGE 1...

As low pressure tracks east from Ontario into Quebec late tonight into Sunday morning, the system's cold front will push southeast across our area. There is limited moisture with this system, so only isolated to scattered snow showers are expected and mainly across higher terrain areas.

After the cold front moves through, colder air aloft will filter in resulting in lake effect snow developing due to Conditional lake induced instability and a W-NW flow. The ~290 degree trajectory favors the SW. Adirondacks and W. Mohawk Valley Sun afternoon into early evening, where 1-3" of snow could accumulate where the most persistent bands occur. Outside of the lake effect, NW winds will increase with gusts of 25-35 mph developing in most areas. Temperatures will likely peak late morning to early afternoon, then falling the rest of the day. Lake effect snow will diminish Sun evening as the flow veers to 305 degrees, limiting to central NY.

KEY MESSAGE 2...

Late Mon night into Tue, a clipper system quickly approaches from the upper Great Lakes and SE Canada in a fast NW flow regime. This looks to be a progressive, but fairly vigorous system. There is still uncertainty in the track of the surface cyclone, with the ECWMF ensembles showing the cyclone center tracking north of our area, while the GFS ensembles indicate more of a southerly track over our area. A southerly track would result in a colder/snowier scenario, but even the northerly track would result in at least some accumulating snow, but turning milder Tue P.M. (35-40F) favoring snow mixing with rain in lower elevations. Will stay closer to the NBM for now, but account for wetbulb effect and leaning slightly snowier Tue P.M.

Forcing from isentropic lift and a short wave aloft will lead to a period of snow late Mon night through at least Tue morning. The Tue P.M. timeframe is less certain due to possible ptype issue of rain mixing with snow in lower elevations. Confidence should increase as the system gets closer over the next few days. At this time will mention preliminary snow amounts of 2-4" in valleys with 3-6" in the higher terrain. Greatest amounts in favored upslope areas of the SW Adirondacks. Latest 24-hr NBM probs for snowfall indicate a 45-85% chance for > 2" (greatest in the mountains) and a 30-50% chance for > 4" in the higher terrain. Will continue to monitor trends for a possible Winter Weather Advisory issuance if confidence continues to increase.

KEY MESSAGE 3...

After a period of seasonably cool temperatures Christmas Eve through Christmas Day, temperatures look to trend above by late week. Another potential clipper system could bring precipitation in late Christmas Day to Fri timeframe, with NBM indicating mainly rain at this time. However, depending on timing and the eventual track of the clipper there could be some wintry precip, especially at higher elevations. Confidence is low at this time. Will monitor trends as post-holiday travel could be affected.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Through 00z Monday...As of 6:20 PM EST, flying conditions are VFR at all terminals, with VFR conditions expected to prevail through most if not all of the TAF period. High clouds increase tonight, with SCT (POU/PSF) to BKN (ALB/GFL) mid and high clouds tomorrow morning. ALB/GFL could see a few snow showers tomorrow morning ahead of a cold front, and have used VCSH groups to highlight this as coverage of snow showers looks fairly isolated. No snow showers expected at POU/PSF. Behind the front, mainly SCT to BKN mid-level clouds persist through the end of the TAF period at all terminals. Some lake effect snow showers could make it to ALB/GFL tomorrow afternoon/evening, which was highlighted with a prob30 group. Confidence in the lake effect band placement and timing remains low, so this will likely need to be refined with future TAF issuances.

Winds tonight will be from the S/SE at 5-10 kt at GFL/POU and 10- 15kt at ALB/PSF with gusts of 20-25kt, strongest at ALB. Winds may briefly weaken and switch to the SW ahead of the cold front tomorrow morning, then abruptly switch to the W/NW behind the front at 10- 15kt with gusts of 25-35kt through tomorrow evening. Strongest winds and gusts expected at ALB/PSF. Have also added LLWS tonight for all terminals with low-level jet at 2000 ft strengthening to 35-50kt from the S/SW. LLWS concerns diminish around/prior to daybreak as the low-level jet weakens to 25-35kt and veers to the W/SW.

Outlook...

Sunday Night: Low Operational Impact. Breezy. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: High Operational Impact. Likely SN. Tuesday: High Operational Impact. Definite RA...SN. Tuesday Night: Moderate Operational Impact. Breezy. Chance of RA...SN. Wednesday: Low Operational Impact. Breezy. NO SIG WX. Wednesday Night: Low Operational Impact. NO SIG WX. Christmas Day: Moderate Operational Impact. Chance of RA...SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.